Electric alarm-bell



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Electric Alarm Bell. No. 242,511. Patented June 7,1881..

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MOSES Gr. CRANE, OF NEWTON, MASSACHUSETTS.

ELECTRIC ALARM-BELL.

SPECIFICATION forming part of Letters Patent No. 242511, dated June 7, 1881.

Application filed January 3, 1881.

To all whom it may concern:

Be it known that I, MOSES G. CRANE, of Newton, county of l\[iddlesex, State of Massachusetts, have invented a new and useful lmprovement in Electrical Apparatus, ot' which the following description, in connection with the. accompanying drawings, is a specification.

My invention relates to electrical apparatus, and is shown embodied in an electro-mechanical bell,such as employed in tire-engine houses for striking tire alarms, such a bell being also adapted for any use requiring single delinite blows to be struck under the control of an electric current applied by an operator controlling the circuit at any point the: cof-as, for example, the signal-bells ot' steanrvessels, and

so on.

Thepresentinventionconsistsinnovel mechanism i'or transmitting the power from the actuating weight or spring' to the bell-hammer; also, in novel detent mechanism whereby the movements of the mechanism are controlled by the armature of the electro-magnet, the said 'detent mechanism being applicable to any aplarge movement of the armature away fromll the poles of its magnet, to restore the said armature to a position near to the poles ot' the magnet, and retain it there by a suitable catch until it is attracted by the said magnet, when by the said attraction, and in the further movement oi' the armature toward the poles ot' the magnet caused thereby, the said armature is disengaged from the said catch and left free to make its long movement away from the poles of the magnet when released by the demagnetization thereof. ln the patent referred to the said catch was disengaged from the armature when the magnet is charged by the magnetic force thereof, it being operated by a secondary armature, by the movement of which toward thepoles of the magnet the catch is disengaged from the main armature,so that when the magnet is demagnetized themain armature is free to fall back from the poles of the (Model.)

magnet, and at the same time the catch is released and brought into position to engage the armature when mechanically moved up near to the poles of the magnet. That arrangement required special devices therein described to insure the proper sequence ot' the movements ofthe main and auxiliary armatures, and also to overcome the residual-y magnetism, both ot' which are rendered unnecessary by the present invention, inwvliich the catch is operated by amechanical force, shown as its weight; but it might be a spring which removes itt'rom engagement with the armature as soon as the said armature is attracted,it being held in engagement with the said armature, whileunattracted by the back pressure thereof from the magnet due to its retractive force.

In the present embodiment of my invention the bell-hammer in its normal position rests upon the short arm of a detent-lever, which is prevented from turning on its pivot lo allow the bell-hammer to move by the engagement of the long arm of the said lever with a projection on the armature ot' the electro-magnet, when held near to the poles thereof, either by a mechanical catch or by the attraction ofthe said magnet. 'lhe mechanical catch is so arranged as to remain engaged by the armature, preventing its backward movement from the poles ot' the magnet only when the said armature tends to move backwardunder the intluence ot' its retractor-in this instance a spring, but it might be its own weight; but as soon as the armature is att acted and moves up to the poles of the magnet the said catch is released and moved aside, leaving the armature tree to fall back a considerable distance from the magnet when again demagnetized. When the armature thus falls back it releases the long arm of the detent-lever, which is then turned on its pivot by the hammer acting on its short arm until the said hammer passes oit from the said lever and is wholly released. The bell-hammer is in this instance hung as a pendulum, and after striking its blow upon the bell is held by the detent-lever suspended at a point considerably above that which it would assume under. the action ot' gravity alone, so that when released the saidbell-ham mer makes its back-stroke away from the bell under the action of gravity.

The bell-hammer arm is provided with a wrist- IOO pin connected with a link connected at its other end with the detent-lever, so that just as the bell-hammer is completing its back-stroke the said link pushes the said lever back to its original position, while the lever itself, after it has passed the projection on the armature, raises the said armature nearly to the poles of the magnet and places the catch beneath it, so that it is in position to be again acted upon by the magnet and moved with a small expenditure of magnetic force, owing to its close proximity to the poles.

An actuating-pawl connected with the bellhammer is moved thereby in its back-stroke into engagement with a tooth of the main acteating-wheel, the said pawl being g'uided by a guide liXed to the frame-work, and as it strikes the said tooth with the momentum of the bellhammer making its back-stroke it causes a slight backward movement of the said wheel, and thus allows a dctaining-pawl pivoted on the frame-work, and previously held by the pressure ot the toothed driving-wheel in engagement therewith, to disengage the said wheel, which then operates on the actuatingpawl connected with the bell-hammer, and causes the said hammer to make its forwa rd stroke and sound the bell.

A guide connected with the bell-hammer operates, while it is thus making its forward stroke, to place the detaining-pawl in position to engage the next tooth of the wheel to the one it was last disengaged from, so that the actuating-wheel in causing the belthammer to make its stroke is moved forward one tooth and then stopped.

The short arm ofthe detent-lever is provided with a pawl, which turns aside to let the bellhammer pass in its forward stroke, but then immediately engages it to prevent it from making another back-stroke, or operatingfnrther, until it has been released by the movement of the detent-lever and connected pawl together, which takes place after the attraction and release of the armature by the magnet, as hereinbefore described.

Figure 1 is a front elevation of a bell-striking apparatus embodying my invention, the parts being in their normal position and no current flowing through the electro-magnet; Fig. 2, an end elevation thereof, showing the detent mechanism at the right hand of Fig. 1 Fig. 3, a detail showing a rear view of the armature and its catch in the position shown in Fig. 1; Fig. 4, a detail of the same parts, but in the position assumed when the magnet is charged and the catch consequently disengaged therefrom; Fig. 5, a detail illustrating the operation of the detent-lever, the full lines showing its long arm engaged by the armature and its short arm holding the bell-hammer arm, the hammer itself being removed, and the dott-ed line showing the armature back and the detent-lever turned aside to release the hammer-arm; and Fig. 6, a detail showing the hammer just at the end of its back-stroke, away from the bell, the detent-lever and armature restored to their normal position, and the actuating-paw! connected with the hammerarm engaged with the actuating-wheel, and the detaining-pawl disengaged therefrom, to canse the hammer to make its forward stroke.

The bell-hammer a, is supported on an arm,

a', pivoted at 2 in a proper position to swing back and forth in the bell or gong b and strike the edge thereof in its forward stroke. After the bell-hammer a has made its forward stroke and sounded the bell, a is engaged, as shown in Fig. 1 and full lines. Fig. 5, by the springcatch c, pivoted upon the short arm ot' thedetent-lever d, itself pivoted at 3, and is thus prevented from making another back-stroke, preparatory to again striking the bell, until the said lever is turned on its pivot, as shown in dotted lilies, Fig. 5, to allow the hammerarm to pass by the end of the said catch. The detent-lever is prevented from thus turning under the weight of the hammer c thereon bv the engagement of a projection, 4, at the end of its long arm with a projection, 5, on the armature c, pivoted at (i and controlled b v the electro-magnetf and retracting-springj.

rllhe projections 4 5 are so situated that they engage one another while the arinatnre isnear or attracted to the poles ot' its magnet; but when the said armature, after beingattraeted, is released by the demagnetization of the said magnet it falls far enough back from the poles thereof, as shown in dotted lilies, Fig. 5, to carry the projection 5 beyond the range ofthe projection 4 on the dctent-lever, leaving the said lever free to turn on its pivot under the action of the weight of the bell-hammer, rest ing 011 the catch c, sufficiently to allow the said hammer to pass by the said catch, as indicated by dotted lines, Fig. 5, and fall, under the action of gravity, to the position shown in Fig. 6, thus making its back-stroke.

A connecting bar or link, g, pivoted at one end to a wrist-pin, g,connected with the hammer arm a', is provided at its other end with a slot, 7, embracing a stud, l1., on the detent* lever el, the said stud resting at about the middle ofthe said slot when the parts are in their normal position, as shown in Fig. 1, so that the detent-lever is free to turn, as indicated in Fig. 5, to release the hammer-arm, the said stud being brought in this movement to the end ofthe said slot, which limits the movement of the detent-lever in this direction.

In the downward movement ofthe hammer in making its back-stroke, as just described, the bar g is moved toward the said stud and carries it and the connected detent-lcver back from the position shown iu dotted lines, Fig. 5, to its original position, (shown in Figs. 1 and 6,) the projection 4 of the said lever passing above the projection 5 ot' the armature, which still remains in its lower position, remote from the poles of the magnet. The detent-lever is provided with a friction-roller, d', which, when the said lever is thus moved back or restored to its original position, as just described, rst comes against a spring, i, con- IOO IIO

Ythe magnet.

nected with the armature-catch j, pivoted at 8, thereby pressing the upper edge., 9, of the said catch against a pin, k, on the side of the armature c, and immediately thereafter the said roller engages an incline, 10, on the under face ot the said armature and raises it toward the poles ot" the magnet, lifting the. pin k above the edge 9 of the catchj, so that the said catch is permitted to turn on its pivot to bring its end beneath the said pin, and thus retain the armature in its position near to the poles of A stop-pin, w, limits the movement ot' the detent-lever when pushed back by the bar g. The projection 5 ot the armature is by this operation brought and retained inline with the projection ofthe detent-lever, which will consequently be engaged thereby. as shown in Fig. 1.

The armature-catchj has a linger, 1l, at its `upper end, which, by its engagement willi the pin k on the armature, prevents the end ot' the armature from being carried beyond thesaid 4pin by the pressure ofthe roller d on the spring 1T, and the said catch is provided with a connter-weight, j', which tends to turn it on its pivot in the opposite direction to that in which it is moved by the roller d.

Then the hammer a begins to make its up or forward stroke to sound the bell, as herein- Aafter described, the bar g is moved away from the stud h, and the deteul-lever allowed to turn back until stopped by the engagement of the projections 4 5, after which, -in the turther movement ot' thebar g, its slotted part? merely travels over the said stud. In this movement of the detent-lever from its extreme forward position, shown in Fig, to its normal position,

Fig. 1, the roller d tirst recedest'rom theincline 1() and allows the armature to rest with the pin k on the end ot' the catch j, as shown in Fig. 3, after which the said roller recedes from the spring 'i of the said catch, which is, however. prevented from falling` from beneath the pin It, under theintluence ot' the counter-weight j', by the friction ofthe said pin on the end ofv the catch, or bythe slight projection 12 at the end of the. edge 9. The armature and catch thus remain engaged, and the former prevented from receding from the magnet, as shown in Fig. 3, as long as the said armature tends` to move in this direction under the influence of its retracting force; but as soon as the armature is attracted and drawn wholly up to the poles ot' its magnet the pin k is removed from the end ot' the catch j and raised above the projection 12 thereon, so that the said catch turns 011 its pivot, under the iniiuence ot' the weightj,'until arrested by the linger 11 coming in contact with a shoulder, 13, on the armature e, as shown in Fig. 4, the said catch being thus removed from the path ot' the pin k, so that the armature is free to fall when released by the demagnetization of the magnet f.

The function of the spring t' is to permit the roller d to operate it in its forward movement without moving the stop j until the said roller has subsequently raised the armature and allowed the catch to move under the secondary action ofthe spring, to that in the return movement ot' the said roller d the armature may be dropped hy lhe disengagement ot' its inclinelU before the catch is permitted to move backby the said roller-a necessary sequence ot' operations which would not take placeit` the catch were positivey engaged by the said roller.

An actuating-pawl,m, connected with the hammer-arm a near its pivotal point, and provvided with a guide-pin, 14, engaging a guide, n, fixed to the trame-work, is brought in the back-stroke otl the hammer, just atter the detent-lever has been moved hack to its normal position, (shown in Fig. 1.) and the armature raised and caught, as previously described, into engagement with a. tooth ot' the actuating wheel o, connected in the usual manner with a mainspring, p, or equivalent motive force, tendingto turn it in the direction ot' the arrow. The momentum ot' the hammer in its downward or back stroke causes the wheel o opposite to the arrow thereon, when theactuating-pawl m strikes its tooth, and by this backward movement the pressure of the tooth 2Uis removed from the detaininglpawl 1' pivoted to the frame-work, and the said pawl drops until Ya projection, l5, thereon rests upon the guide t connected with the bell-hammer arm a. The actuating-wheel is thus released, and by its pressureon the pawl m causes the hammer to make its forward stroke to hit the bell b, and in the same movement the guide t raises the detaining-pawl after the. tooth 20, previously held thereby, has passed it, so that just as the hammer has nearly reached the bell the said detaining-pawl engages the next tooth, 21, of the wheelo. Thehammer completesits stroke .by the momentum acquired,and the pawl mis drawn slightly away from the tooth that has just. actuated it. and falls ont ot' engagement therewith, it again resting on the guide a, by which it will be carried in thenextmovement vot' the hammer into engagement with thetooth i'ollowiugthe one last acted upon. ln its for Ward stroke the bell-hammer turns the springcatch c asideon its pivot, the said catch spring ing back as soon as the hammer has passed, and thus preventing its back-stroke until the detent-lever turns on its pivot 3, as before described; and it will be seen that in its normal condition, as shown in Fig. 1, the actuatingwheel 0 is entirely disconnected from the pawl m and the bell-hammer.

It is obvious that the force of springs might beused,instead of gravity, to operate thebellhammer in its back-stroke, and to withdraw the catch j from beneath the armature; and the moving parts might, it' needed, be all coun- Iterbalanced when thus operated by springs, so as to work independently of their position, as wcuid be desirable for ship-signals.

A spring, c2, ou the back of the bell-ham IOS IIS

mer serves, in cooperation with astop-piii, xc, on the frame-work, to stop the bell-hammer and prevent it from hitting the other side ot' the bell in its back-stroke, the recoil of the said spring assisting the actuating-wheel in prod uciiig a strong blow in the forward stroke.

In operation, if the circuit; ofthe magnet f is normallyopeii. the parts will be as in Fig. 1, the armature being held np by the catch, as in Fig. 3, and when the circuit is closed, or if it ieiiiaiiis normally closed, as in tire-alarm systenis, the ariiiatnre will be attracted, as in full lines, Fig. 5, and the eatchj withdrawn therefrom, as in Fig. 4. \Vhen the circuit is now broken the armature t'alls back from the m-,igiiet, releasing tliedeteiit-lever, which turns and lets the hammer make its back-stroke, during which the detent-lever aiid armature are restored to their normal position, Figs. l and 6, and at the end of which back-stroke tlieactiiating-wheel is brought into engagement with the actuating-pawl and hammer, and at the same time released, and thereafter causes the hammer to make its forward strokeaiid hit the bell, after which the parts remain in the position shown in Fig. 1 until the circnitisclosed, and then broken when another blow is struck. By this detent mechanism theI bell or other mechanism retained motionless after once being operated, whether the circuit is closedor open, and is again operated only when the circuit is opened after having been previously closed. rlhe magnetic force is liever required to move the armature but a short distance, its other movements being caused by its relractor and the restoring mechanism.

I claim- 1. The actuating-wheel and the retainingpawl therefor, combined with the bell-llaminer aiiii and the actnating-pawl, and guide, for the actuating-pawl, connected with the said arm, and the guide for the aitiiatiiig-pa\\],

lixed upon the frame-work, arranged and to operate substantially as described, and for the purpose set forth.

2. Theactuating-wheel, thchammer-arm and detent therefor, and the actuating-pawl connected with the said hainmer-arm, the said parts being arranged iii combination, as described, whereby the said pawl is disengaged from the wheel while thehaminer-arm is engaged by its detent, substantially' as described.

3. A mechanical motor and deteiit lever therefor, and an electro-magnet and its arma ture, combined with the catch or prop for the said armature, provided with acoiinter-weight, or equivalent, and restoring mechanism operated by the said motor, whereby the said deteiit-lever is restored into engagement with the aiiiiatiire and the armature engaged by its catch in the movement of the motor, which takes place on the release of the detent, substantially as described.

4. The detent-lever, armature, and catch or iprop therefor, and the restoring device coi1- iiected with the said lever, whereby the Inoveiiieiit ot" the lever into engagement with the armature c iiises the said armature io be moved up to the poles ot' the magnet and engaged alid held there by the said catch, substantially as described.

5. The electro-magnet and itsarmalure, movable between a back-stop and a position near to the poles of the magnet, combined with the catch or prop for the said armature, properly arranged to engage and hohl it., when in its position near to the poles ot' the magnet, but unattracted thereby, and the counter-weight, or equivalent, to remove the said catch from engagement with the said armature when at tracted by the-magnet, substantially as and for the purpose desci ibed.

6. A detent-lever, and armature-lever and stop therefor, provided with a spring to be engaged by l hedeteiit-lever, the said armature being` provided with a pin to engage the said catch, and with an incline to be engaged by the detentlever, the said parts being arranged iii combination, as described, whereby, when the deient-lever is moved into engagement with the armature, it raises the said armature up to the poles ot' its magnet and brings the catch into engagement with the pin thereof to retain it there, substantially as described.

1n testimony whereot'l have signed my name to this specitication in the presence of two subscribing witnesses.

Witnesses: MOSES G. CRANE.

Jos. P. LIVERMORE, BERNICE J. N OYES. 

